Electron discharge device control system



Jan. 24, 1939. E. KOBEL 3 ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed June 22, 1953 5 Sheets-Sheet l Jan. 24, 1939. E. KOBEL 2,145,088

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed June 22, 1933 5 Sheets-Sheet 2 :L 3 nuv w HEW u:

a E am i Em Jan. 24, 1939. E KQBEL 2,145,088

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed June 22, 1933 5 Sheets-Sheet 3 "MANY; J 4 l ST;

lmllhll II I Jan. 24, 1939. I E KOBEL 2,145,088

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Filed June 22, 1933 5 Sheets-Sheet 4 5 Sheets-Sheet 5 6 v .i a Z. F L TE?1 E. KOBEL Filed June 22, 1955 Jan. 24, 1939.'

ELECTRON DISCHARGE DEVICE CONTROL SYSTEM Patented Jan. 24, 1939 PATENT OFFICE ELECTRON DISCHARGE DEVICE CONTROL SYSTE Ernst Kobel, Ennetbaden, Switzerland, assignor to Aktiengesellschaft Brown Boveri & Cie., Baden, Switzerland, a, joint-stock company of Switzerland Application June 22, 1933, Serial No. 677,069 In Germany July 13, 1932 35 Claims.

This invention relates to improvements in control means for electron discharge devices and more particularly to means for releasing and for interrupting the flow of current between two electrodes in an electron discharge device of the vapor type.

This application is in part a continuation of prior application Serial No. 630,545, filed August 26, 1932, for Electron discharge device; and in another application, Serial No. 703,349, filed December 21, 1933, Patent No. 2,097,490, dated November 2, 1937, are claimed features of the electron discharge devices shown and described herein.

In electron discharge devices the current generally flows between a non-electron emitting electrode or anode and an electron emitting electrode or cathode when the anode is made positive by suitable means with respect to the potential of the cathode, which is generally adopted as datum for all potentials in the circuits of the device. Such flow of current may occur during periods cf different lengths from the several anodes and in sequences involving the several anodes depending upon the connection of the device with the circuits associated therewith to form systems performing different functions such as rectifying, inverting, frequency changing, direct current voltage converting or current interrupting systems. In such systems it is frequently desired to control the flow of current within the device in such a manner as to cause such current to flow during periods differing from the periods during which such current would otherwise flow as a result of the connections of the device. By the use of suitable discharge controlling means, the release of the current from any of the positive electrodes may be retarded and the period of flow of such current may thus be diminished at will. The flow of such current through the circuits associated with the device generally causes the potential relations of the electrodes to be modified so that an anode may become positive with respect to a cathode and current may flow therebetween for periods during which the energizing means of the device tend to maintain such anode negative with respect to the cathode. In general, the flow of current from one positive electrode is interrupted upon release of the flow of current through another positive electrode so that the periods of current flow through the several positive electrodes of an electron discharge device are necessarily consecutive.

By providing separate and distinct means for releasing and for interrupting the flow of current through each anode of the device, such current iicw may be controlled to occur during periods of arbitrary length and to begin at any desired instant. To initiate the flow of current through anode, the electron emission at the associated cathode may be initiated or, if the cathode is in a continuous electron emitting condition, the discharge between the anode and the cathode may be released by electromagnetic, electrostatic or mechanical means. The space wherein the discharge is to occur is preferably previously brought to an ionized condition by an auxiliary discharge. Upon interruption of the flow of current through an anode, the magnetic energy stored in the circuits associated with such anode is preferably discharged by means which may be identical with the means producing the ionizing discharge.

It is, therefore, among the objects of the present invention to provide a control system for an electron discharge device of the gas or of the vapor type whereby the flow of current between an anode and a cathode is released and is interrupted independently of the variations of the source energizing such anode.

Another object of the present invention is to provide a control system for an electron discharge device of the gas or of the vapor type whereby the flow of current between an anode and a cathode is released and is subsequently interrupted at will during the period when such anode is positive with respect to the cathode.

Another object of the present invention is to provide a control system for an electron discharge device of the gas or of the vapor type whereby the flow of current between an anode and a cathode is released and subsequently interrupted by suitable discharge controlling means.

Another object of the present invention is to provide a control system for an electron discharge device of the gas or of the vapor type whereby the flow of current between an anode and a cathode is released and is subsequently interrupted by suitable energization of a control electrode associated with the anode.

Another object of the present invention is to provide a control system for an electron discharge device of the gas or of the vapor type whereby the flow of current between an anode and a cathode is released or interrupted by impression of suitable potential impulses on the anode.

Objects and advantages other than those above described will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. l diagrammatically illustrates one embodiment of the present invention applied to the control of an electron discharge device employed in a rectifying inverting system whereby the flow of current through an anode is released upon momentary connection of such anode with the associated control electrode and is interrupted by negatively energizing such control electrode at will;

Fig. 2 diagrammatically illustrates a portion of a modified embodiment of the present invention diifering from the embodiment illustrated in Fig.

l in that the control electrodes are permanently connected with the associated anodes through suitable impedance means;

Fig. 3 diagrammatically illustrates a portion of a modified embodiment of the present invention differing from the embodiment illustrated in Fig. 1 in that the flow of current through each anode is interrupted by impressing a negative potential impulses on such anode;

Fig. 4 diagrammatically illustrates a portion of a modified embodiment of the present invention differing from the embodiment illustrated in Fig. 1 in that the flow of current through each anode is released by impressing a positive potential impulse on such anode;

Fig. 5 diagrammatically illustrates a portion of a modified embodiment of the present invention differing from the embodiment illustrated in Fig. 2 in the connection of the discharge interrupting means and in the use of auxiliary discharge devices in the circuits of such means;

Fig. 6 diagrammatically illustrates a portion of a modified embodiment of the present invention differing from the embodiment illustrated in Fig. 5 in the method of connection of the discharge interrupting means;

Fig. 7 diagrammatically illustrates a portion of a modified embodiment of the present invention likewise differing from Fig. 5 in the connec tion of the discharge interrupting means;

Fig. 8 diagrammatically illustrates a portion of a modified embodiment of the present invention differing from the embodiment illustrated in Fig. 2 in that each control electrode is alternately energized at positive and at negative potentials over auxiliary discharge devices;

Fig. 9 diagrammatically illustrates a portion of a modified embodiment of the present invention differing from the embodiment illustrated in Fig. 8 in the use of grid controlled auxiliary discharge devices and in the method of connections of the circuits thereof; and

Fig. 10 diagrammatically illustrates another embodiment of the present invention applied to the control of an electron'discharge device employed for regulating the output voltage of a direct current generator.

Referring more particularly to the drawings by characters of reference, reference numeral H3 in Fig; 1 designates an alternating current supply line of any desired number of phases and energized at any voltage of any frequency, and herein represented as a three phase line. It is assumed that it is desired to cause the flow of current between line I6 and a direct current line II, l8 over an electron discharge device l9 having anodes 2| and a cathode 22. Cathode 22 is herein represented as being of the mercury pool type and it is assumed that device I9 is provided with suitable well known discharge igniting and maintaining means (not shown). It will, however, be

ductor l7 will be positive with respect to conductor I8 and cathode 22. If line I6 is provided with a neutral conductor, anodes 2| may be connected directly with the phase conductors of line l6 and conductor I! may be connected with the neutral conductor thereof. It is, however, generally preferred to connect anodes 2| with line |6 by means of a transformer having a primary winding 23 connected with line l5 and a secondary winding 24 having a plurality of phase portions severally connected with anodes 2| and connected in star to form one or several neutral points. In the present embodiment Winding 24 is formed with two neutral points connected with conductor H by means of an interphase transformer 25.

Each anode 2| is insulated from the wall or device H? by an insulator 26, and cathode 22 is preferably insulated from such wall by an insulator 21 as is Well known in the art. Each anode 2| is provided with a control electrode 28 which is preferably so dimensioned as to permit not only blocking of the flow of current between the associated anode and cathode 22 but also permitting easy interruption of such fiow of current upon negative energization of such control electrode by means of a suitable source. To obtain interruption of the current flow between an anode and the cathode upon negative energization of the control electrode, the positive charges of the ions present in the space between the anode and the control electrode must be removed by the control electrode and the associated source at a rate greater than the rate of appearance of such charges within such space due to collisions of electrons with vapor atoms or due to wandering from the space outside the control electrode through the openings thereof; in addition to neutralization of the ioniccharges, the electrons produced at the cathode or in the space outside of the control electrodes are then repelled due to the negative potential of the control electrode and no further transport of charges can occur at the anode. To obtain such result without resorting to the use of a source of such high voltage as to introduce disturbances into the operation of the device, it is necessary to employ a control electrode having dimensions maintained within predetermined limitations. Such control electrode may have all the openings thereof which are available for the passage of the discharge, so dimensioned that the ion sheaths formed about the several portions of the control electrode struc ture entirely fill all such openings when such control electrode is unenergized or is energized at negative potentials of any magnitude. The total area of such openings must be limited and should preferably not exceed 40% of the area of the anode in contact with the discharge. The distance between the control electrode and the anode should be comparable with the mean free path of the electrons, and the area of the surfaces of the control electrode in contact with the space contained between such electrode and the associated anode, plus the total area of the surfaces of such control electrode defining the openings thereof, should be greater than the total crosssectional area of such openings. The lower limit of the ratio of such areas is dependent upon the distance between the control electrode and the anode and should exceed the value 2.5 when such distance is equal to the mean free path of the electrons.

When control electrode 28 is made of sheet metal, the surface area above defined may not be available and may then be obtained by providing internal projections on control electrode 28 or by adding another member 29 inserted between control electrode 28 and anode 2|. Member 29 may be directly connected with control electrode 28 or may be connected therewith through impedance means or may be separately energized in which latter case member 29 must be insulated from control electrode 28 and must be provided with a separate insulated connection. The function of such member is only to collect some of the ions present in the space between the control electrode and the anode during interruption of the current but such member is otherwise without eifect on the operation of the anode.

Each anode 2| is preferably provided with an excitation anode 3| and with an arc guide 32 which is supported by insulator 26 and permits the passage therethrough of the discharge to anode 2|. Excitation anode 3| is connected with anode 2| by impedance means such as a resistance 33 to permit surges produced upon interruption of current through anode 2! to be discharged over anode 3| which is always operable to carry current irrespective of the energization of control electrode 28. Control electrode 28 is connected with a source of positive energization through resistance 34 and a distributor 35 having a brush 3! driven by the rotor 38 of a synchronous motor. In the present embodiment, supply transformer Secondary Winding 24 is utilized as a source of energization for control electrode 28 and distributor 3B is accordingly provided with pairs of contacts which may be bridged by brush 3?, one contact of each pair being connected with one control electrode and the other contact of each pair being connected with the portion of winding 2 connected with the anode associated with the control electrode. Control electrode 28 is also connected through a resistance 4| with a segment of another distributor 42 having a brush 43 driven by the rotor 44 of another synchronous motor, and receiving a negative potential from a battery 41 connected with conductor i8.

Rotors 3B and 44 of the synchronous motors are each assumed to carry a plurality of windings and the stators of such motors are assumed to be provided with windings 39 and 46 respectively energized from line IS. The windings of rotors 38 and 44 are energized by means of a suitable source of direct current herein shown as consisting of a transformer 52 energized from line it and associated with a pair of rectifying devices 53. A mid-tap in the secondary winding of transformer 52 is directly connected with one winding of each armature and devices 53 are connected with two other windings in each armature through regulating resistances 54 and 56 operable as voltage dividers. Such resistances are provided with movable taps which may be moved in opposite directions by means of a lever 5'. to simultaneously adjust the distribution of current in armatures 38 and 44 in opposite directions.

If member 29 is energized separately from con-- trol electrode 28, such member is connected through a resistance 48 with one segment of a distributor 49 having a brush 5| driven by rotor 44 and receiving a negative potential from battery 41. The negative potential impressed on member 29 need not be as high as the negative potential impressed on control electrode 28; such potential need only be suflicient to cause positive ions to transfer their charges to member 29 without having any other action on the flow of current to anode 2|.

In operation, assuming that the system is connected as shown and that line I6 is energized to supply current to line H, l8, anodes 2| sequentially and periodically receive alternating voltages from the several portions of winding 24. When an anode 2| is positive, the associated electrode 3| is likewise positive and carries a current limited by resistance 33 but which is sufiicient for ionizing the space through which the discharge from anode 2| to cathode 22 is to flow. As long as control electrode 22 is not connected with anode 2| or with batter .1, such control electrode takes a negative charge from the electrons wandering within the device and prevents the flow of current between anode 2| and cathode 22. While anode 2| is still positive, control electrode 28 is 0011-, nected therewith at a predetermined instant by brush 3?. Such control electrode therefore becomes positive, carries current and releases the fiow of current between anode 2| and cathode 22. The initiation of such current flow is facilitated by the ionizing action of the discharge flowing between electrode 3| and cathode 22. Brush 3! then disconnects control 28 from anode 2| without thereby aifecting the flow of current between ancde 2! and cathode 22. termined length of time brush 43 connects control electrode 28 with battery 4! and brush 5| simultaneously connects member 29 with such battery. The ions present in the space between control electrode 28 and anode 2| transfer their charges to control electrode 28 and member 29 and electrons present outside of control electrode 28 are repelled and the flow of current between anode 2| and cathode 22 is thereby interrupted. After such interrupting process is completed, brushes 43 and 5| may again disconnect control electrode 28 and member 29 from battery 4'! and the flow of current through anode 2| will not be reestablished until control electrode 28 is again connected with anode 2|. The magnetic energy stored in windings 23 and 24 at the moment of interruption of the current through anode 2| tends to maintain such flow of current and consequently causes the appearance of a voltage surge on anode 2i such surge is then discharged by means of electrode (ii and resistance 33. The actual process of the interrupting action of the control electrode was explained above in the light of the generally accepted theory of the transport of electric charges and may therefore not be correct. That the desired result is, however, actually obtained was found by experiment as described by applicant in an article published in the February 1, 1933, issue of the Schweizerischer Elektrotechnischer Verein Bulletin pages 41 to 48.

The process above described is sequentially repeated for each anode of device I 9 during each cycle of the voltage of line l6. The times of energization of control electrodes 28 from anode 2| and from battery 41 may be varied by movement of lever 57. Such lever causes the distribution of current in the windings of rotors 38 and 44 to be varied in such manner that one of the rotors will lead the rotating field induced by the associ- After a prede-:

ated stator winding while the other rotor will lag by an equal angle behind the rotating field produced by the associated stator winding. The release of the flow of current through anode 2| is therefore advanced or retarded and the interruption of such flow of current is retarded or advanced by an equal amount. Current, therefore, flows through anode 2| during a period of variable length but such current remains in constant phase relation with the corresponding anode voltage and the current drawn from line I6 is therefore at a substantially constant power factor for all conditions of regulation of the current through device I9. If the period of flow of current through an anode 2| is shorter than the unregulated period of flow would be, the periods of flow of current through successive anodes are no longer consecutive. In the present embodiment, however, as a result of the connection of winding 24 with interphase transformer 25, current is always carried simultaneously by two anodes receiving voltages of difierent phases and being parts of two three-phase systems in which the current lapses do not occur simultaneously so that the flow of direct current through line Il- |8 remains uninterrupted. I

If device I9 is to invert direct current received from line H, I8 into alternating current supplied to line I6, lever 51 is so adjusted that control electrodes 28 will permit the associated anodes to carry current when receiving negative voltages from the associated portions of winding 24. Such flow of current may be controlled to occur during any desired portion of the voltage cycle as, with the use of the particular control electrodes described, it is not necessary to depend upon the voltage maintained in line I6 by voltage wave or frequency determining means to effect the transfer of the flow of current from one anode to the succeeding anode. The operation of the system remains substantially the same as during rectifying operation. Under either condition of operation the space through which the anode discharge is to occur is ionized by means of electrode 3| energized from a suitable source such as winding 24; the flow of current is released by means of control electrode 28, distributor 36 and a suitable source such as winding 24; the flow of current is interrupted by means of control electrode 28 and member 29, distributors 42 and 49 and battery 41, and the voltage surge then appearing upon anode 2| is discharged by means of electrode 3| and resistance 33.

In the embodiment partially illustrated in Fig. 2, member 29 is not illustrated and is assumed to be either omitted or permanently connected with control electrode 28. Distributor 36 is also omitted and control electrode 28 is illustrated as being permanently connected with anode 2| by resistance 34. Distributor 42 is replaced by a plurality of distributors such as 58 and 59 having brushes such as 6| driven by the rotor of a synchronous motor 62 energized from line I6. Each distributor is provided with a segment such as 64 a connected with the associated control electrode, 1

and with an idle segment such as 66. The position of the segments of the distributor'may be adjusted by movement of a lever 63.

, The operation of the system illustrated in the present embodiment is substantially the same as the operation of the embodiment illustrated in Fig. 1. In the present embodiment, the discharge path of anode 2| is again ionized by the flow of a discharge between electrode 3| and cathode 22. The flow of current from anode 2| is prevented as long as control electrode 28 receives a negative potential from battery 41 through resistance 61, brush 6| and segment 64 of distributor 58. Such flow of current is released when brush 6| is no longer in contact with segment 64 and engages with segment 66 whereupon control electrode 28 becomes positively energized from line |6 through the supply transformer 23 and 24. Such flow of current is interrupted when brush 6| is again in contact with segment 64 and control electrode 28 is again negatively energized from battery 41. The voltage surge then appearing at anode 28 is discharged by electrode 3| through resistance 33. In the present embodiment, control electrode 28 must remain negatively energized from battery 4'! during the periods during which anode 2| is positively energized but is not to carry current as control electrode 28 becomes positive as soon as distributor 58 disconnects such control electrode from battery 41. In the present embodiment no means were provided for independently adjusting the times of the release and of the interruption of the current through each anode so that the length of the periods during which each anode carries current is constant and leads the voltage or lags behind the voltage in response to movement of lever 63 and the current drawn from line I6 has a variable leading or lagging power factor. The periods of operation of the several anodes are then necessarily consecutive and the current delivered by device I9 is uninterrupted.

In the embodiment illustrated in Fig. 3 each of the steps in the operation of controlling the flow of current through an anode is controlled by entirely separate means. The ionization of the discharge path of anode 2| is produced by the flow of a constant current from a source of current such as battery 68 through resistance 33 and electrode 3| to cathode 22. The flow of current through anode 2| is released by means of control electrode 28 upon positive energization thereof through distributor 36 from a source of positive potential such as a battery 69. Such flow of current is interrupted upon discharging of a negatively charged condenser I3 through anode 2| and cathode 22. Such operation is controlled by means of a distributor II having a brush I2 driven in common with brush 3! by synchronous motor 62 energized from line I6. Distributor 1| is provided with a plurality of segments such as I4 connected with a source of negative potential such as between anode 2| and cathode 22 is no longer maintained and control electrode 28 prevents such discharge from being reestablished sothat the flow of current between anode 2| and cathode 22 is interrupted. Condenser I3 receives, from anode 2|, a positive charge which is dissipated upon the next connection of condenser I3 with battery Hi. In the present embodiment a common discharge electrode I8 is provided for all anodes 2| and is connected therewith through suitable impedance means such as resistances I9. The segments of distributors 36 and II are adjustable in opposite directions by movement ofa lever During such flow, of current through condenser I3 the discharge 1! thereby providing for the adjustment of the flow of current at a constant power factor for all adjustments of the system as in the embodiment illustrated in Fig. 1. By suitable initial adjustment of the segments of distributors 36 and "H such flow of current may be made to occur at unity power factor or at any lagging or leading power factor under all conditions of operation.

In the embodiment illustrated in Fig. 4 the discharge path between anode 2! and cathode 22 is ionized by the current flowing from electrode 3| and received from winding 2 as in the embodiment illustrated in Fig. l. The flow of current through anode 2| is released by impressing, between such anode and cathode 22, a positive surge of higher magnitude than the normal operating voltage of device i9. such magnitude being selected at a sufiiciently high value to cause an electrical breakdown of the space between anode 2! and cathode 22 even when control electrode 28 is not positively energized. To obtain this result, a distributor 82 provided With a brush 8! driven by motor 62 is used for alternately positively charging a condenser 83 from a battery 84 through resistance 85 and discharging such condenser sequentially through the several anodes of device I9. The flow of current through anode 2! thus initiated is interrupted b means of distributor 42 and battery 4! as in the embodiment illustrated in Fig. 1. The potential surge appearing on anodes 2! upon interruption of the flow of current therethrough is discharged partly over electrode 3! but the greater portion thereof is utilized for charging condenser 13 through one segment 15 of distributor 7!. The positive charge thus received by condenser 73 is then discharged through a resistance '15 over a segment 14 of distributor H. In the present embodiment, the initiation of the flow of current through each anode may be adjusted by lever 8'! controlling the position of the segments of distributor 82 and the times of interruption of such flow of current are controlled by the lever 89 which jointly controls the position of the segments of distributors 42 and H.

In the embodiment illustrated in Fig. 5 the discharge path of anode 2! is ionized by the flow of current from winding 2% through resistance 33 and electrode 3| as in the embodiment illustrated in Fig. 1. Control electrode 28 is then negatively energized from anode 2! through resistance 34, a battery 9! and one of the portions of the secondary winding 92 of a transformer having a primary winding 93 energized from line it. Such energization is effected over an auxiliary discharge device 94 which is in a conductive condition as long as the potential impressed on the electrodes thereof is greater than a predetermined value. When the voltage impressed on the circuit of device 95 by winding 92 increases in the positive direction so as to oppose the voltage of battery 9!, the voltage impressed cn device 94 decreases until such device ceases to be conductive. At such instant, control electrode 28 becomes energized only from Winding 24 through resistances 83 and 89 and releases the flow of current through anode 2i. When the voltage impressed on device 94 by winding 92 becomes increasingly negative such voltage will reach the value at which device 9 becomes conductive and control electrode 28 then becomes negatively energized from anode 2! through resistance 39, battery St, a portion of winding 92 and device 94. The energization of control electrode 28 by such means causes the flow of current through anode 2| to be interrupted. The potential. surge then appearing on anode 2! is discharged by electrode 3! through resistance 33. The moments of release and of interruption of the flow of current through anode 2'! may be simultaneously adjusted by varying the amount of battery 9! utilized in the circuit of device 94.

In the embodiment illustrated in Fig. 6, resistance 39 and battery 9! are omitted and control electrode 28 is connected with conductor !8 over a discharge devi"e 95 which may be similar to device 99, through one of the star connected portions of the secondary winding 9'! of a transformer having a primary winding 96 energized from line 59, and through resistance 6'! and battery 41. Winding 99 may be connected with line !6 through an induction regulator 98 operable to vary the voltage impressed on winding 96, such variations being effected in constant or variable phase relation according to the method of construction of regulator 98. The operation of the present embodiment is entirely similar to the operation of the embodiment illustrated in Fig. 5 but the moments of release and of interruption or" the current flowing through anode 2! in the present embodiment are preferably adjusted by varying the voltage of winding 96 by means of regulator 98.

In the embodiment illustrated in Fig. '7 control electrode 28 is connected with conductor I8 over one of the phase portions of winding 92 and through an auxiliary discharge device 99 provided with a control electrode. The anode of device 99 is connected with winding 92, the cathode thereof is connected with conductor [8 through resistance I99, and the control electrode thereof is connected with a variable tap of a resistance tel connected with anode 2i and connected with conductor ll through a reactor I92. The discharge path of anode 2! is ionized by the flow of current from winding 24 through resistance 33 and electrode 3i. Control electrode 28 being positively energized from winding 24 through resistance 34 releases the flow of current through anode 2!. At such instant the control electrode of device 99 receives a negative potential and device 99 is not conductive. At a later instant such control electrode receives a positive potential and device 99 is conductive and impresses on control electrode 28 a negative potential from winding 92, thereby causing control electrode 28 to interrupt the flow of current through device 2!. The potential surge appearing on electrode 3! is then discharged through resistance 33 and electrode 3!. During the remaining period of the cycle of the voltage of line it, the control electrode of device 99 again becomes negative and control electrode 28 again receives the same potential as anode 2!.

In the embodiment illustrated in Fig. 8, control electrode 28 receives a positive potential from winding 92 when such potential reaches the value at which device 94 becomes conductive, thereby releasing the flow of current through anode 25. When the voltage of .wind'ng 92 decreases below such value, device 94 ceases to be conductive and control electrode 28 may then be negatively energized by means of battery 41, winding 97 and device 95 as in the embodiment illustrated in Fig. 6. In the present embodiment, the moment of positive energization of control electrode 28 may be adjusted by means of a voltage regulator I93 similar to regulator 98 and inserted between line [6 and winding 93.

The potential surge appearing on anode 2I upon interruption of the flow of current therethrough is discharged through resistance 33 and electrode 3|.

In the embodiment illustrated in Fig. 9, control electrode 28 is energized by means of battery 84 through an auxiliary discharge device IM similar to device 93 having the anode thereof connected with battery 84 and the cathode thereof connected with control electrode 28 through resistance 34. The control electrode of device I04 is energized from a movable tap of a resistance I96 connected with anode 2 I and connected with conductor I? through a condenser IN. The means for negatively energizing control electrode 28 are the same as here illustrated in the embodiment of Fig. 7. In the present embodiment the discharge path of anode 2! is ionized by the flow of current from winding 24 through resistance 33 and electrode 3i. The control electrodes of devices I I14 and 99 are then negatively energized with respect to the associated cathode and devices I04 and 99 are non-conductive. The control electrode of device IIM becomes positive with respect to the associated cathode and device I04 becomes conductive, thereby impressing on control electrode 28 the potential of battery 84. The flow of current through anode 2| is accordingly released. The control electrode of device Hi4 again becomes negative and device I04 is no longer conductive so that device 99 may impress on control electrode 28 a negative potential to cause interruption of the flow of current through anode 2| as in the embodiment illustrated in Fig. '7.

In the embodiment illustrated in Fig. 10, anodes 2|, control electrode 28, electrode 3| and cathode 22 are part of a single anode electron discharge device I08 operating in a manner similar to that of device I9. Device N38 is utilized for controlling the output voltage of a direct current generator having an armature I09 supplying a direct current line IIZ and a field winding III energized from an exciter having an armature H3 and a shunt field H4. The current of winding II I flows partly through a rheostat H6 and partly through device I 98 to permit regulation thereof. The current flowing through device I08 flows in greater part through anode H but a small part of such current flows through resistance 33 and electrode SI, such flow not being controlled and maintain ing the discharge path of anode 2| in a constant state of ionization. Control electrode 28 is connected through a resistance I I1 and an auxiliary discharge device 95 with the positive terminal of line I I2 and, through resistance I I7 and a second resistance H8, with a movable tap of a voltage divider I2! energized from line H2. Cathode 22 is connected with an intermediate point of voltage divider I2 I.

In operation, assuming that generator IIl9,I It is delivering current to line I I2 at a voltage which is below the desired value, the voltage impressed on device 85, which is proportional to the voltage of line I I2, is insufiicient to render device conductive. Control electrode 28 is then positively energized from eXciter I I3, I I 4 through resistance 34 and releases the flow of a direct current through anode 2 I. Such flow of current does not reach the steady value thereof immediately because of the inductance of winding III, and the voltage impressed on line M2 by armature I09 in creases slowly in response to the increase of the flow of current through device I08 and winding I I I. The voltage of line I I2 then increases beyond the desired value, thereby causing the voltage impressed on device 95 to increase beyond the value at which such device becomes conductive.

Device 95 then carries current and control'elec- V trode 28 becomes negatively energized from voltage divider I2I through device 95 and resistance I II. Such energization causes the interruption of the flow of current through anode 2! so that only the current carried by electrode 3| continues to flow through device I618. The potential surge then appearing on anode 2I is also discharged by electrode 3|. The flow of current through winding III is thereby decreased and the output voltage of armature I09 decreases below the desired value, thereby causing a periodic repetition of the cycle of operation above described.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims. 7

It is claimed and desired to secure by Letters Patent:

1. In a system for controlling the flow of electric current, an electron discharge device of the vapor arcing" type having an anode and a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetween, and having a control electrode, energizing means for said control electrode to cause the same to release the said flow of current, and a second energizing means for said control electrode to cause the same to deionize the space between the said anode and control electrode to thereby interrupt the said flow of current during periods when said anode and cathode are subjected to potential differences sufficient to maintain said arcs, the said control electrode comprising a surface positioned from the arcing surface of said anode at a distance not greater than the mean free path of the electrons involved a in sustaining said arcs, and having a plurality of apertures forming paths for the said flow of current and defined by opposite surfaces distant by not more than twice the. thickness of ion sheaths produced by the said second energizing means.

2. In a system for controlling the flow of electric current, an electron discharge device of the vapor type and having an anode and a cathode and a control electrode associated with 'the anode, energizing means for the control electrode to cause the same to release the flow of current between the anode and the cathode, asecond energizing means for the control electrode to cause the same to interrupt the flow of current between the anode and the cathode, and means for ionizing the discharge path between the anode and the cathode.

3. In a system for controlling the flow of electric current, an electron discharge device of the vapor arcing type having an anode and a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetween, and having a control electrode positioned adjacent said anode, energizing means for said control electrode to cause the same to release the saidfiow of current, a second energizing means for said control electrode to cause the same to deionize the space between said anode and said control electrode to thereby interrupt the said flow of current, and means for discharging voltage surges occurring between said anode and cathode.

4. In a system for controlling the flow of electric current, an electron discharge device of the vapor type and having an anode and a cathode, energizing means operable to release the flow of current between the anode and the cathode, a second energizing means operable to interrupt the flow of current between the anode and the oathode, means for ionizing the discharge path between the anode and the cathode, and means for discharging voltage surges occurring between the anode and the cathode.

5. In a system for controlling the flow of electric current, an electron discharge device of the vapor type and having an anode and a cathode and a control electrode associated with the anode, energizing means operable to release the flow of current between the anode and the. cathode, a second energizing means operable to interrupt the flow of current between the anode and the cathode, and common means for ionizing the discharge path between the anode and the cathode and for discharging voltage surges occurring therebetween.

6. In a system for controlling the flow of electric current, an electron discharge device of the vapor type and having an anode and a cathode and having a control electrode associated with the anode, energizing means operable to release the flow of current between the anode and the cathode, a second energizing means to interrupt the flow of current between the anode and the cathode, and an excitation anode connected with the anode and having a discharge path partly coincident with the discharge path of the anode.

'7. In a system for controlling the flow of electric current, an electron discharge device of the vapor arcing type and having an anode and a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetween, and having a control electrode, energizing means for said control electrode and including a source of potential positive with respect to the potential of said cathode and operable to release said flow of current, and a second energizing means for said control electrode and including a source of potential negative with respect to the potential of said cathode and operable to cause said control electrode to deionize the space between said anode and control electrode to thereby interrupt the said flow of current during periods when said anode and cathode are subjected to potential differences sufficient to maintain said arcs, the said control electrode comprising a surface thereof positioned from the arcing surface of said anode at a distance not greater than the mean free path of the electrons involved in sustaining said arcs, and having a plurality of apertures forming paths for said flow of current and defined by opposite walls distant not more than twice the thickness of ion sheaths produced therein by the said second energizing means.

8. The method of controlling the flow of current by way of arcs between a main anode and cathode of an electron discharge device of the vapor arcing type by means of a control electrode and an auxiliary anode positioned adjacent said main anode comprising the continual successive. steps of establishing an auxiliary arc in the discharge path between said auxiliary anode and cathode, releasing said flow of current by applying a potential positive with respect to the potential of said cathode to the said control electrode, and in interrupting the said flow of current during periods when said main anode and cathode are subjected to potential differences sufficient to maintain the first said arcs by deionizing the space between said anode and control electrode by impressing on the latter a potential negative with respect to said cathode.

9. The method of controlling the flow of cur-- rent way of arcs when established between an anode and a cathode of an electron discharge device of the vapor arcing type by means of a control electrode positioned adjacent said anode consisting in releasing said flow of current by impressing on said control electrode a potential positive with respect to the potential of said cathode, interrupting the said flow of current by deioniaing the space between said anode and control electrode by impressing on the latter a potential negative with respect to the potential of said cathode, and discharging the voltage surge occurring between said anode and cathode upon interruption of the flow of current therebetween.

10. ihe method of controlling the flow of current by way of arcs when established between an anode and a cathode of an electron discharge device of the vapor arcing type by means of a control electrode positioned adjacent said anode consisting in establishing an ionized condition in the discharge path between said anode and cathode, releasing said flow of current by impressing on said control electrode a potential positive with respect to the potential of said cathode, interrupting the said flow of current by deionizing the space between said anode and control electrode by impressing on the latter a potential negative with respect to the potential of said cathode, and discharging the voltage surge occurring between said anode and cathode upon interruption of the flow of current therebetween.

11.111 a system for controlling the flow of electric current, an electron discharge device of the vapor arcing type having an anode and a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetwee-n, and having a control electrode, energizing means operable to produce the flow of current between said anode and cathode, a second energizing means for impressing on said control electrode potential positive with respect to the potential of said cathode to thereby release the said flow of current, and means for impressing on said control electrode potential negative with respect to the potential of said cathode to thereby deionize the space between said anode and control electrode to thereby interrupt the said fiow of current during periods when said anode and cathode are subjected to potential differences sufficient to maintain said arcs, the said control electrode being positioned across the path of said arcs and having a plurality of apertures of a total cross section area of approximately forty percent of the arcing surface of said anode and having a total area in contact with the space contained between the said control electrode and anode, plus the total. area of the surfaces forming said apertures, of not less than two and a half times the total cross section area of said apertures.

12. In a system for controlling the flow of electric current, an electron discharge device of the vapor type having an anode and a cathode and having a control electrode associated with said anode, energizing means operable to produce the flow of current between said anode and said cathode, means for impressing a potential impulse on anode positive with respect to the potential of said cathode for releasing the flow of current between said anode and said cathode, and means 7| iii) for negatively energizing said control electrode with respect to the potential of said cathode for interrupting the flow of current between said anode and said cathode.

13. In a system for controlling the flow of electric current, an electron discharge device of the vapor type having an anode and a cathode and having a control electrode associated with said anode, energizing means operable to cause the fiow of current between said anode and said cathode, a second energizing means for positively energizing said control electrode with respect to the potential of said cathode for releasing the flow of current between said anode and said cathode, means for negatively energizing said control electrode with respect to the potential of said cathode for interrupting the flow of current between said anode and said cathode, impedance means connected with said anode, and an excitation anode arranged within the discharge path between said anode and said cathode and connected with the last said means.

14. In a system for controlling the flow of electric current, an electron discharge device of the vapor type having an anode and a cathode and having a control electrode associated with said anode, energizing means operable to cause the flow of current between said anode and said cathode, a second energizing means for positively energizing said control electrode with respect to the potential of said cathode. for releasing the flow of current between said anode and said cathode, means for impressing a potential impulse on said anode negative with respect to the potential of said cathode for interrupting the flow of current between said anode and said cathode, impedance means connected with said anode, and an excitation anode arranged within the discharge path between said anode and said cathode and connected with the last said means.

15. In a system for controlling, the flow of electric current, an electron discharge device of the vapor type having an anode and a cathode and having a control electrode associated with said anode, energizing means operable to cause the flow of current between said anode and said cathode, means for impressing a potential impulse on said anode positive with respect to the potential of said cathode for releasing the flow of current between said anode and said cathode, means for negatively energizing said control electrode with respect to the potential-of said cathode for interrupting the flow of current between said anode and said cathode, impedance means connected with said anode, and an excitation anode arranged within the discharge path between said anode and said cathode and connected with the last said means.

16. In a system for controlling the flow of electric current, an electron discharge device of the vapor type having an anode and a cathode and having a control electrode associated with said anode, energizing means operable to cause. the flow of current between said anode, and said cathode, a condenser connected with said cathode, means for impressing a potential impulse on said anode positive with respect to the potential of said cathode for releasing the flow of current between said anode and said cathode, and means for negatively energizing said control electrode with respect to the potential of said cathode and for simultaneouslyconnecting said condenser with said anode for interrupting the flow of current between said anode and said cathode.

17. In a system for controlling the flow of electric current, an electron discharge device of the vapor arcing type having an anode and a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetween, and having a control electrode, means for energizing said control electrode to release said flow of current, and means comprising an alterhating current transformer for impressing on said control electrode potential of such sign and magnitude as to deionize the space between said anode and control electrode to thereby interrupt said flow of current during periods when said anode and cathode are subjected to potential differences suficient to maintain said arcs, the said control electrode being positioned across the path of said arcs and having a plurality of apertures of a total cross section area of approximately forty percent of the arcing surface of said anode and having a total area in contact with the space contained between the said control electrode and anode, plus the total area of the surfaces forming said apertures, of not less than two and a half times the total cross section area of said apertures.

18. In a system forcontrolling the flow of electric current, an electron discharge device of the vapor arcing type having an anode and a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetween and having a control electrode positioned adjacent said anode, means for energizing said control electrode to release the said flow of current, and means comprising an auxiliary electron discharge device for impressing on said control electrode potential of such sign and magnitude as to deionize the space between said anode and control electrode, to thereby interrupt the said flow of current.

19. In a system for controlling the flow of electric current, an electron discharge device of the vapor arcing type having an anode and a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetween and having a control electrode positioned adjacent said anode, means for energizing said control electrode to release the said flow of current, and means comprising an alternating poten tial transformer and an auxiliary electron discharge device for impressing on said control electrode potential of such sign and magnitude as to deionize the space between said anode and control electrode, to thereby interrupt the said flow of current.

20. In a system for controlling the flow of electric current, an alternating current line, a transformer connected with said line, an electron discharge device of the vapor arcing type connected with said transformer and having an anode and 'a cathode constituting spaced electrodes for the flow of current by way of arcs when established therebetween, and having a control electrode, means energized from said transformer for energizing said control electrode to release the said flowof current, and means for impressing on said control electrode potential of such sign and magnitude as to deionize the space between said anode and control electrode to thereby interrupt the said flow of current during periods when said anode and cathode are subjected to potential difierences sufiicient to maintain said arcs, the said control electrode having a surface spaced from said anode by approximately the mean free path of the electrons involved in sustaining said arcs and having apertures therethrough of a total cross section area of approximately forty percent of the arcing surface of said anode, and having a total area within the space contained between said control electrode and anode, plus the total area of the surfaces forming said apertures, of not less than two and a half times the total cross section area of the said apertures.

21. In a system for controlling the flow of electric current, an alternating current line, a transformer connected with said line, an electron discharge device of the vapor type connected with said transformer and having an anode with an associated control electrode and a cathode, means energized from said transformer for energizing the control electrode to release the flow of current between the anodes and the cathode, and means including an alternating potential transformer, a source of direct current potential, and an auxiliary electron discharge device connecting the last said transformer and said source with the control electrode to interrupt the fiow of current between the anode and the cathode.

22. In a system for controlling the flow of electric current, an electron discharge device of the arcing type including a casing, an electron emitting electrode, a plurality of anodes extending into the casing and control electrodes associated with each of the anodes, an alternating current line connected with the anodes, a direct current line connected with the device, means severally associated with said anodes for producingv arcs to the electron emitting electrode, and a phase shifter connected with said alternating current line and with said direct current line to supply potential to said control electrodes and to said means.

23. In combination with an electric current converting device of the vapor arcing type having a cathode, and a plurality of anodes forming electrodes for the flow of current therefrom to said cathode by way of arcs sequentially established thereto, of a plurality of control electrodes severally associated with said anodes, and means comprising a source of current connected with said control electrodes operable to impress potential thereon at such recurring periods and of such sign and magnitude as to control the moments of establishment of said arcs, the said source of current and said electrodes being cooperatively operable to interrupt said arcs.

24. In a system of the character described, an electric current converting device of the vapor arcing type having a cathode, a plurality of anodes forming electrodes for the flow of current therefrom to said cathode by way of arcs sequentially established thereto, and control electrodes severally associated with said anodes, and means comprising a source of current connected with and operable to impress potential on said control electrodes at such recurring periods and of such sign and magnitude as to prevent establishment of said arcs to the associated ones of said anodes, the dimensions and the positioning of said control electrodes and the impression of said potential thereon being at such recurring periods as to interrupt said arcs to the associated ones of said anodes.

25. In a system of the character described, an electric current converting device of the vapor arcing type having a cathode, a plurality of anodes constituting electrodes for the flow of current therefrom to said cathode by way of arcs sequentially established thereto, and control electrodes severally associated with said anodes, and means comprising a source of current connected with and operable to alternately impress potential sequentially on said control electrodes at such recurring periods and of such sign and magnitude as to facilitate and to prevent establishment of said arcs, the dimensions and the positioning of said control electrodes relative to the said anodes being such as to interrupt said arcs thereto during periods of impression of said potential on the associated ones of said control electrodes of sign and magnitude to prevent establishment of said arcs.

26. In a system of the character described, an electric current converting device having a cathode, a plurality of main anodes constituting electrodes for the flow of current therefrom to said cathode by way of arcs established thereto, auxiliary anodes severally associated with said main anodes, and control electrodes, means comprising a source of current connected with and operable to sequentially impress on said auxiliary anodes potential of such sign and magnitude as to establish supplemental arcs thereto at such recurring periods as to facilitate establishment of said arcs to the associated ones of said main anodes, and means comprising a second source of current connected with and operable to impress potential sequentially on said control electrodes at such recurring periods and of such signs and magnitude as to cooperate with the first said means in facilitating the establishment of the first said arcs and to prevent establishment thereof, the dimensions and the positioning of said control electrodes relative to. said anodes being such as to interrupt the first said arcs during periods of impression of said potential on the associated ones of said control electrodes of sign and magnitude to prevent establishment of such said arcs.

27. In a system of the character described, an electric current converting device of the vapor arcing type having a cathode, a plurality of main anodes constituting electrodes for the flow of current therefrom to said cathode by way of arcs sequentially established thereto, control electrodesseverally associated with said anodes, auxiliary anodes severally associated with the first said anodes, and means comprising a source of current connected with and operable to alternately impress potentials sequentially on said control electrodes and said auxiliary anodes at such recurring periods and of such signs and magnitude as to prevent establishment and to facilitate and control the moment of establishment of said arcs, the said means including means operable to vary the moments of impressions of said potentials, and the dimensions and positioning of said control electrodes relative to said anodes being such as to interrupt said arcs thereto upon impression of said potential on the associated said control electrodes and auxiliary anodes of sign and magnitude to prevent establishment of said arcs.

28. In the system of the character described, an electric current converting device comprising an evacuated chamber having a cathode of vaporization material supported therein, an anode depending into said chamber and forming with said cathode electrodes for the flow of current by way of arcs established therebetween, a shield supported within said chamber about said anode and forming a guide for said arcs, a control electrode supported within said shield adjacent said anode, and means connected with said control electrode operable to alternately impress thereon potentials of such signs and magnitudes and during such recurring moments as to prevent the establishment and to facilitate and control the moments of establishment of said arcs, the dimensions and positioning of said control electrode relative to said anode being such as to interrupt said arcs during the moments of impression of the said potential thereon of sign and magnitude to prevent establishment of said arcs.

29. In combination with an electric current converting device comprising a casing forming an evacuated chamber having a cathode contained therein, a main anode depending into said chamher in spaced relation with said cathode and forming therewith electrodes for the .flow of current by way of arcs when established therebetween, a shield supported within said chamber about said anode and forming a guide for said arcs, and a control electrode supported within said shield adjacent said anode, and means connected with said control electrode operable to alternately apply thereto potentials of such signs and magnitudes and during such recurring moments as to prevent and control the moments of establishment of said arcs, of an auxiliary anode supported within said shield, means connected with said auxiliary anode and with said cathode operable to apply thereto potential of such sign and magnitude as to establish auxiliary arcs therebetween to thereby facilitate establishment of the first said arcs, and means connecting said auxiliary anode with the said main anode for discharging voltage surges occurring thereon, the dimensions and positioning of said control electrode being such as to interrupt the first said arcs during the moments of application thereto of the said potential of sign and magnitude to prevent establishment of the first said arcs.

30. The combination with an electron discharge device of the vapor type comprising a casing forming a chamber containing a cathode, a main anode constituting with said cathode spaced electrodes for the flow of current by way of arcs when established therebetween, a control electrode associated with said anode, and an auxiliary anode associated with said control electrode and constituting with said cathode spaced electrodes for the fiow of current by way of arcs when established therebetween, of means comprising a source of current connected with said control electrode and with said auxiliary anode for applying potentials thereto ofsuch sign and magnitude and during such recurring moments as to control the moments of initiation of the first said arcs and to initiate the second said arcs to thereby intensify the ionization of the space about saidv control electrode, whereby the initiation of 'the first said arcs is facilitated.

31. The combination with an electron discharge device comprising a casing forming a chamber containing a cathode, a plurality of main anodes constituting with said cathode spaced electrodes for the flow of current by way of arcs when sequentially established therebetween, a plurality of control electrodes severally associated with said anodes, and auxiliary anodes severally associated with said control electrodes constituting with said cathode spaced electrodes for the fiow of current by way of arcs when sequentially established therebetween, of .means comprising a source of current connected with said control electrodes and with said auxiliary anodes for applying potentials thereto of such sign and magnitude and during such recurring moments as to control the moments of initiation of the first said arcs and to initiate the second said arcs, to thereby intensify the ionization of the space about said control electrodes, whereby the initiation of the first said arcs is facilitated.

32. In a system for controlling the flow of electric current, an electron discharge device of the vapor type comprising a cathode, a main anode constituting with said cathode spaced electrodes for the flow of current by way of arcs when established therebetween, and a control electrode associated with said anode, means comprising a source of current connected with said control electrode operable to alternately apply potentials thereto of such signs and magnitudes as to prevent the establishment of said arcs and to control the moments of initiation thereof, an auxiliary anode comprising an element of said device constituting with said cathode spaced electrodes for the flow of current by way of arcs when established therebetween, and means comprising a source of current connected with said cathode and with said auxiliary anode for applying potential thereto of such sign and magnitude as to initiate and maintain the second said arcs, the path of the second said arcs being such as to intensify the ionization of the space about said control electrode to thereby facilitate the initiation of the first said arcs.

33. In a system for controlling the flow of electric current, an electron discharge device comprising a cathode, a main anode constituting with said cathode spaced electrodes for the flow of current by way of arcs when established therebetween, and a control electrode associated with said anode, means comprising a source of current connected with said control electrode operable to alternately apply potentials thereto of such signs and magnitude as to prevent the establishment of said arcs and to control the moments of initiation thereof, an auxiliary anode comprising an element of said device and constituting with said cathode spaced electrodes for the fiow of current by way of arcs when established therebetween, means comprising a source of current connected with said cathode and with said auxiliary anode for applying potential thereto of such sign and magnitude as to initiate and maintain the second said arcs, the path of the second said arcs being such as to intensify the ionization of the space about the said'control electrode to thereby facilitate the initiation of the first said arcs, and means connecting the said auxiliary anode with the said main anode for discharging voltage surges occurring thereon.

34. A system for transmitting energy between direct current and alternating current circuits or .between alternating current circuits of different frequencies, phases and voltages, comprising polyphas-e networks of inductive windings and a plurality of gas discharge valves, each having main electrodes and a control electrode cooperating therewith, interconnecting said circuits, a first source of substantially steady potential, means connected to said source including a distributing device for applying successive discharge initiating potential to the control electrodes of said valves, a second source of substantially steady potential, further means connected to said second source including a second distributing device for applying negative voltage impulses to successively interrupt the current through said valves associated with the successive phase windings, said distributing devices having stationary and moving parts, means for operating said moving parts in synchronism with the alternating current, and means for displacing the stationary parts relative to one another.

35. A system for transmitting energy between direct current and alternating current circuits, or between alternating current circuits of different frequencies, phases and voltages, comprising polyphase networks of inductive windings and a plurality of gas discharge valves cooperating therewith for interconnecting said circuits, said valves having cathodes, anodes, and control electrodes; a source of potential; a. first control means connected to said source and operating in synchronism with the alternating current for sequentially impressing discharge starting po- ERNST KOBEL. 

